Archaebacteria are able to tolerate high temperature as well as high acidity.
These bacteria are chemoautotrophic which obtain energy for synthesis of food by oxi iising sulphur, leader anaerobic conditions they oxidise sulphur to sulphuric acid.

Thermoacidophiles are able to tolerate high temperature as well as acidity, due to the presence of
(i) Branched chaiix lipids in the cell membranes.
(ii) Special resistant enzymes capable of operating under aerobic conditions.